I would like to know if someone have a practical experience with CDC (Change Data Capture) OTHER than Golden Gate with exadata

Yes I have some experience with Shareplex on Exadata.
We have random stability, corruption and performance issues on the Shareplex side which we run in dbfs on Exadata.
Hope this answers your question.
Regards,
Tycho

it doesnot say anything about the downside of not having a subscriber in CDC

Can you explain the question?
What does a subscriber do?
In Shareplex you have for instance a capture and a post process but I don not know a subscriber.....
Even without this subscriber it works (well most of the time) so I do not see a downside yet.
Regards,
Tycho